Calculating energy savings results is keeping like golf score. If you ever been on the green, understanding the meaning of CUSUM is trivial.
Baseline – how machine is supposed to work or worked before retrofit – is a par.
CUSUM – a cumulative sum of deviations from baseline – is score.
If CUSUM is above par, machine wastes energy compared to baseline period. Something went wrong.
If CUSUM below par, machine work more efficiently than during baseline period, you are getting energy savings.
Tell this to you CFO and you will never have to explain value of CUSUM again.